New Sensor to Measure the Microencapsulated Active Compounds Released in an Aqueous Liquid Media Based in Dielectric Properties in Radiofrequency Range.

In recent years, the general and scientific interest in nutrition, digestion, and what role they play in our body has increased, and there is still much work to be carried out in the field of developing sensors and techniques that are capable of identifying and quantifying the chemical species involved in these processes. Iron deficiency is the most common and widespread nutritional disorder that mainly affects the health of children and women. Iron from the diet may be available as heme or organic iron, or as non-heme or inorganic iron. The absorption of non-heme iron requires its solubilization and reduction in the ferric state to ferrous that begins in the gastric acid environment, because iron in the ferric state is very poorly absorbable. There are chemical species with reducing capacity (antioxidants) that also have the ability to reduce iron, such as ascorbic acid. This paper aims to develop a sensor for measuring the release of encapsulated active compounds, in different media, based on dielectric properties measurement in the radio frequency range. An impedance sensor able to measure the release of microencapsulated active compounds was developed. The sensor was tested with calcium alginate beads encapsulating iron ions and ascorbic acid as active compounds. The prediction and measurement potential of this sensor was improved by developing a thermodynamic model that allows obtaining kinetic parameters that will allow suitable encapsulation design for subsequent release.

Analysis of Apple Candying by Microwave Spectroscopy.

Process control in the industry requires fast, safe and easily applicable methods. In this sense, the use of dielectric spectroscopy in the microwave range can be a great opportunity to monitor processes in which the mobility and quantity of water is the main property to produce a quality and safety product. The candying of fruits is an operation in which the samples are first osmotically dehydrated and then exposed to a hot air-drying operation. This process produces changes in both the structure of the tissue and the relationships between water, the solid matrix and the added soluble solids. The aim of this paper is to develop a dielectric tool to predict the water/sucrose states throughout the candying of apple, by considering the complexity of the tissue and describing the different transport phenomena and the different transition processes of the sucrose inside the sample.

Gums induced microstructure stability in Ca(II)-alginate beads containing lactase analyzed by SAXS.

Previous works show that the addition of trehalose and gums in ß-galactosidase (lactase) Ca(II)-alginate encapsulation systems improved its intrinsic stability against freezing and dehydration processes in the pristine state. However, there is no available information on the evolution in microstructure due to the constraints imposed by the operational conditions. The aim of this research is to study the time course of microstructural changes of Ca(II)-alginate matrices driven by the presence of trehalose, arabic and guar gums as excipients and to discuss how these changes influence the diffusional transport (assessed by LF-NMR) and the enzymatic activity of the encapsulated lactase. The structural modifications at different scales were assessed by SAXS. The incorporation of gums as second excipients induces a significant stabilization in the microstructure not only at the rod scale, but also in the characteristic size and density of alginate dimers (basic units of construction of rods) and the degree of interconnection of rods at a larger scale, improving the performance in terms of lactase activity.

Characterization of a Sea Buckthorn Extract and Its Effect on Free and Encapsulated Lactobacillus casei.

Probiotics are bacteria that can provide health benefits to consumers and are suitable to be added to a variety of foods. In this research, viability of immobilized Lactobacillus casei in alginate with or without sea buckthorn lipid extract were studied during heat treatment and with an in vitro gastrointestinal model. The characterization of the lipid extract was also done using the UV-Vis spectrometry (UV-Vis), high-performance liquid chromatography photodiode array detection method (HPLC-PDA), gas chromatography coupled with mass spectrometry (GS-MS) and Cryo scanning electron microscopy (Cryo-SEM). During heat treatment, the entrapped probiotic cells proved high viability (>6 CFU log/g), even at temperatures above 50 °C. The rich in monounsaturated fatty acids sea buckthorn fraction improved the in vitro digestion passage regarding the probiotic viability. The survival of the probiotic cells was 15% higher after 2 h in the acidic medium of the simulated gastric fluid in the sample where L. casei was encapsulated with the sea buckthorn extract compared with the samples where no extract was added. Thus, this approach may be effective for the future development of probiotic-supplemented foods as foods with health welfare for the consumers.

Encapsulation of lactase in Ca(II)-alginate beads: Effect of stabilizers and drying methods.

The purpose of the present work was to analyze the effect of trehalose, arabic and guar gums on the preservation of ß-galactosidase activity in freeze-dried and vacuum dried Ca(II)-alginate beads. Freezing process was also studied as a first step of freeze-drying. Trehalose was critical for ß-galactosidase conservation, and guar gum as a second excipient showed the highest conservation effect (close to 95%). Systems with Tg values ~40°C which were stables at ambient temperature were obtained, being trehalose the main responsible of the formation of an amorphous matrix. Vacuum dried beads showed smaller size (with Feret's diameter below 1.08±0.09mm), higher circularity (reaching 0.78±0.06) and large cracks in their surface than freeze-dried beads, which were more spongy and voluminous. Ice crystallization of the beads revealed that the crystallization of Ca(II)-alginate system follows the Avrami kinetics of nucleation and growth. Particularly, Ca(II)-alginate showed an Avrami index of 2.03±0.07, which means that crystal growing is bidimensional. Neither the addition of trehalose nor gums affected the dimension of the ice growing or its rate. These results open an opportunity in the development of new lactic products able to be consumed by lactose intolerance people.

Osmotic dehydration of organic kiwifruit pre-treated by pulsed electric fields and monitored by NMR.

Osmotic dehydration (OD) is a widely used preservation technique that consists in the reduction in food water activity by the immersion of the biological tissue in hypertonic solutions. The aim of this work was to analyze the effect of pulsed electric fields (PEF) in mass transfer as a pre-treatment of the OD using NMR. In this sense, PEF pre-treatments were done using three different voltages (100, 250 and 400V/cm) and 60 number of pulse. The OD of kiwifruit was carried out in 61.5% of sucrose solution at 25°C, for a contact period from 0 to 120min. The water distribution into the cellular tissue was studied by NMR relaxometry. In conclusion, NMR is an excellent technique for quantifying water molecules according to their interactions in the fruit tissue, obtaining the adsorbed water and opening the possibility to apply the BET model to fit the adsorbed isotherm over the whole range of water activity.

Development of a Spectrophotometric System to Detect White Striping Physiopathy in Whole Chicken Carcasses.

Due to the high intensification of poultry production in recent years, white chicken breast striping is one of the most frequently seen myopathies. The aim of this research was to develop a spectrophotometry-based sensor to detect white striping physiopathy in chicken breast meat in whole chicken carcasses with skin. Experiments were carried out using normal and white striping breasts. In order to understand the mechanism involved in this physiopathy, the different tissues that conform each breast were analyzed. Permittivity in radiofrequency (40 Hz to 1 MHz) was measured using two different sensors; a sensor with two flat plates to analyze the whole breast with skin (NB or WSB), and a two needles with blunt-ended sensor to analyze the different surface tissues of the skinless breast. In the microwave range (500 MHz to 20 GHz), permittivity was measured as just was described for the two needles with blunt-ended sensor. Moreover, fatty acids composition was determined by calorimetry techniques from -40 °C to 50 °C at 5 °C/min after previously freeze-drying the samples, and pH, microstructure by Cryo-SEM and binocular loupe structure were also analyzed. The results showed that the white striping physiopathy consists of the partial breakdown of the pectoral muscle causing an increase in fatty acids, reducing the quality of the meat. It was possible to detect white striping physiopathy in chicken carcasses with skin using spectrophotometry of radiofrequency spectra.

Alginate Beads Containing Lactase: Stability and Microstructure.

ß-Galactosidase (lactase) is a widely used enzyme in the food industry; however, it has low stability against thermal and mechanical treatments. Due to this, the purpose of the present research was to analyze the encapsulation of lactase in alginate-Ca(II) beads in order to maintain its enzymatic activity toward freezing, freezing/thawing, and storage. Also, the effect of the addition of trehalose, and arabic and guar gums and their influence on the microstructure as well as on thermal properties and molecular mobility were studied. Lactase was successfully encapsulated in alginate-Ca(II) beads, and the inclusion of trehalose was critical for activity preservation toward treatments, being improved in guar gum-containing systems. The gums increased the Tm' values, which represents a valuable technological improvement. Finally, the presence of secondary excipients affected the microstructure, showing rods with smaller outer diameter and with lower compactness than alginate-Ca(II) beads. Also, bead composition greatly affects the size, shape, and relaxation times.

Development of a dielectric spectroscopy technique for determining key chemical components of apple maturity.

Dielectric measurements (from 500 MHz to 20 GHz) on different standard solutions (K(+), malic acid) with different sugar contents were assayed simulating concentrations of these substances during apple ripening. These assays were performed for considering the potential use of dielectric spectra (500 MHz to 20 GHz) to determine the optimal time for eating the fruit. Good correlations between a newly defined dielectric maturity index and the Thiault index were found. This work presents prospective data of dielectric spectra for certain apple key chemical components in order to consider its potential application as a nondestructive control sensor for the prediction of climacteric fruit maturity.